.........snip
>Greame Finlay, a cell biologist at the University of Auckland, New Zealand,
>writes: "The genetic content of human chromosome 2 is co-linear with
>that of the
>two great ape chromosomes from which it is derived. At band 2q21 lie
>the remains
>of the redundant centromere of one of the ancestral chromosomes.
>Such telomeric
>fusions are familiar phenomena, arising by naturally occurring mechanisms."
>(referring to Martin C.L. et al., "The evolutionary origin of human
>subtelomeric
>homologies - or where the ends begin", Am.J.Hum.Genet. 70 (2002), 972)
>
>Each chromosome needs exactly one centromere and two terminal
>telomeres. Each of
>the two ape chromosomes concerned has its centromere near one of the
>telomeres.
>The fusion occurred (in the haploid state) between the telomeres of the short
>arms. The fusion point between these two ape chromosomes can be recognized in
>the human chromosome 2 as the head-to-head remains of two fused telomeres,
>flanked on one side by the existing centromere inherited from one of the ape
>chromosomes, and on the other side by the centromeric relic of the other ape
>chromosome. Apparently, no essential gene was lost or damaged in the fusion
>process. Telomers are highly repetitive sequences which can easily
>fuse by means
>of unequal crossing-over during replication. The end result of the process was
>the decrease of the (diploid) ape chromosome number of 48 to the 46 of humans.
>
>It represents one of the many extremely strong indications of common
>descent of
>humans and primates. Whether a miracle was involved, we don't know; at this
>point, the processes are quite natural. Whether this was _the_ crucial
>transition (on the physical/biological level) between ape and human, we don't
>know. Whether this has any direct connection (e.g. in time) with
>God's creating
>humans in His image, we don't know, either.
>
>Peter
>
>--
>Dr. Peter Ruest, CH-3148 Lanzenhaeusern, Switzerland
><pruest@dplanet.ch> - Biochemistry - Creation and evolution
>"..the work which God created to evolve it" (Genesis 2:3)

This week's Nature contains the paper on the completion of the
sequence of human Chr. 2 & 4 with more details about the head to head
telomere remnants and the remains of the lost centromere (in the
section on Segmental Duplications. Segments close to telomeres tend
to be duplicated to the near-telomere or near-centromere regions of
other chromosomes. Sure enough, there are segments on either side of
the telomere fusion region which were duplicated to the expected
regions of other chromosomes before the fusion occurred.